A known coffee-cartridge holder is constructed to receive a coffee cartridge whose walls of a filter material between which the ground coffee is present extend horizontally when the cartridge holder is placed on a cup. Coffee is brewed by pouring hot water onto the coffee cartridge in the holder and the brew is received in the cup.
A problem associated with this coffee-filtering method is that during the extraction process foam accumulates in the coffee cartridge between the surface of the ground coffee and the upper one of the horizontally disposed filter walls. This foam presents an additional resistance to the water flowing through, so that the extraction time, i.e. the time taken by the water to flow through the coffee cartridge, is long.
It is the object of the invention to improve the filter device in such a way that the foam produced during the extraction process does not affect or only slightly affects the extraction time.